Hi @Beatriz BV,
This is possible using Time Tables since you know the exact times that each AGV should be operating. I've set up an example Time Table that you can use. The idea is that for any objects that belong to a certain Time Table, you can define what those objects' states are at any given time. In your case, you would use 3 Time Tables, one for each AGV.
For the times that the AGVs are unavailable to work, you will set a downtime using a table or the graph. The image below shows that the AGV using this Time Table (TaskExecuter1) will only operate from 7:00 until 9:00. The other AGVs begin work at 9:00 and 11:00.

These Time Tables can be created for the needs of your model. Here's an example model that you can use for reference: time-table-example.fsm